Microorganism and a process for producing polyols by using the same

ABSTRACT

Trichosporonoides kounosuensis  7E-1 (FERM BP-6572) having taxonomical properties different from those of any known species belonging to the genus Trichosporonoides, and having the ability to efficiently produce a polyol such as erythritol.

TECHNICAL FIELD

The present invention relates to a novel microorganism and a process forproducing polyol by use of the same and in particular to a new strainbelonging to the genus Trichosporonoides, that is, Trichosporonoideskounosuensis 7E-1 (FERM BP-6572), and a process for producing polyol byuse of said strain.

BACKGROUND ART

As microorganisms having been practically used until now in producingpolyol particularly erythritol, there are known two microorganisms i.e.Moniliella tomentosa var. pollinis CBS 461.67 and Trichosporonoidesmegachiliensis SN-G42 (FERM BP-1430) (which is the same as Aureobasidiumsp. SN-G42 (FERM P-8940)). For the former, there are known a series ofprocesses for producing polyol by fermentation of saccharides inindustrial scale (Japanese Patent Publication Nos. 30591/1994,30592/1994, 30593/1994 and 30594/1994). For the latter, there is known anovel microorganism having the ability to produce erythritol as well asa process for producing erythritol by fermentation with saidmicroorganism (Japanese Patent Publication Nos. 11189/1992 and635/1992).

For microorganisms of the genus Trichosporonoides, there is a report ofMarina A. Y. Aoki in the State University of Campinas, Brazil, onconversion of glucose and sucrose into erythritol (BiotechnologyLetters, Volume 15, No. 4, pp. 383-388, April 1993). According to thisreport, the rate of conversion of glucose into erythritol is as high as43.0%, and the rate of conversion of sucrose into erythritol is as highas 37.4%, but the concentration of these saccharides in the culturemedium is as low as 10% (W/V), so there is a problem with production inindustrial scale.

Further, Ueda et al. in Mitsubishi Chemical Co., Ltd. reported that 5strains of the genus Trichosporonoides, that is, Trichosporonoidesoedocephalis CBS 649.66, Trichosporonoides madida CBS 240.79,Trichosporonoides nigrescens CBS 268.81, Trichosporonoides spathulataCBS 241.79, and Trichosporonoides megachiliensis CBS 567.85 can formerythritol from glucose (Japanese Patent Laid-Open No. 154589/1997).However, these microorganisms are not necessarily advantageous forlarge-scale production because the range of their culture temperaturesis as narrow as 25 to 37° C. (suitable temperature of 27-35° C.) and alarge amount of cooling water is required. Regrettably, it is known thatTrichosporonoides nigrescens particularly exhibiting the bestproductivity of 136.0 g/L erythritol does not grow at 37° C. and at aconcentration of 50% glucose (infra).

DISCLOSURE OF THE INVENTION

An object of the present invention is to provide a novel microorganismhaving a high ability to produce polyol, particularly a microorganismproducing a large amount of polyol such as erythritol etc. even atrelatively high temperatures (35 to 39° C.) and at high sugar levels (20to 60%).

Another object of the present invention is to provide a process forproducing polyol inexpensively by use of this microorganism.

The present inventor made extensive studies to find a novelmicroorganism having the ability to produce polyol particularlyerythritol, and as a result, he found that a novel microorganismseparated from a honeycomb solves the aforementioned problem, that is,this microorganism shows good growth at a culture temperature of 35 to39° C. and at a sugar level of 20 to 60% to produce a large amount ofpolyol, and the present invention was thereby completed.

That is, the present invention relates to a novel microorganismbelonging to the genus Trichosporonoides separated from a honeycomb andin particular to Trichosporonoides kounosuensis 7E-1 (FERM BP-6572).

Further, the present invention relates to a process for producing polyolwhich comprises culturing said microorganism and recovering polyol whichmainly contains erythritol, glycerin and ribitol from the culture.

BEST MODE FOR CARRYING OUT THE INVENTION

The novel microorganism of the present invention was separated in thefollowing manner. That is, a honeycomb was cultivated in a mediumcontaining 40% glucose whereby sugar-resistant microorganisms wereselected, and the culture temperature was set at 35° C. wherebymesophilic or thermophilic microorganisms were selected. Then, themicroorganism separated purely by a conventional microbial separationmethod was cultured in a medium containing 30% glucose, and measured forthe amount of polyol accumulated in the culture, whereby a microorganismhaving a high ability to produce polyol, specifically Trichosporonoideskounosuensis 7E-1, was separated.

This microorganism is internationally deposited as FERM BP-6572(transferred on Nov. 12, 1998 from Japanese original deposit No. FERMP-16303, originally deposited on Jul. 3, 1997) with the Patent MicrobialDeposit Center in the National Institute of Bioscience andHuman-Technology, Agency of Industrial Science and Technology of 1-3,Higashi 1-chome, Tsukuba-shi, Ibaraki-ken, Japan.

The mycological properties of Trichosporonoides kounosuensis 7E-1isolated from a honeycomb in Kounosu-shi, Saitama-ken, Japan by thepresent inventor are described in detail as follows. The mycologicalproperties of Trichosporonoides kounosuensis 7E-1 were examined inaccordance with “The Yeasts, A Taxonomic Study, Third Revised andEnlarged Edition”, edited by N. J. W. Kreger-van Rij Groningen, 1984,published by Elsevier Science Publishers B. V., Amsterdam.

1. The states of growth in medium

1) Microscopical observation

(Culture in YM broth at 25° C. for 3 days)

Size of vegetative cell: 4 to 7.5×4 to 12μ

Shape of vegetative cell: spherical, egg-shaped or oval-shaped

State of vegetative cell: multipolar budding

(Slide culture on potato glucose agar at 25° C. for 7 days)

Blastic conidia: formed

Arthrospores: formed

Pseudomycelia: formed

Hypha: formed

2) Culture in liquid medium (Culture in YM broth at 25° C.)

Growth on the surface: film formation

Turbidity: transparent or slightly turbid

Sedimentation: high

Color of the medium: The medium turns pale brown after about 4-dayculture and this color becomes darker, thereafter as the cultureproceeds.

3) Agar (Culture on YM agar at 25° C. for 2 weeks)

Growth: good

Glossy: absent

Pigment: The colonies, as well as the medium, after culture for 1 weekor more turn dark brown.

2. Formation of ascospores

Ascospores are not formed on potato glucose agar, corn meal agar, YMagar, Gorodkowa agar, and acetate medium.

3. Physiological properties

requirement for oxygen aerobic growth temperature 42° C. optimum growthtemperature 31 to 37° C. pH for growth 2 to 10.5 optimum pH for growth 5to 8 assimilation of KNO₃ positive splitting of fat negativedecomposition of urea positive liquefaction of gelatin positiveformation of carotenoid negative formation of organic acids positiveformation of esters positive formation of starch-like substance negativerequirement for vitamin positive color reaction with diazonium blue Bpositive resistance to osmotic pressure 10% sodium chloride positive(growing) 12% sodium chloride negative (not growing) 60% glucosepositive (growing)

4. Fermentability of saccharides

glucose positive lactose negative galactose positive melibiose negativeraffinose negative sucrose positive maltose positive inulin negativeinositol negative

5. Assimilation of carbon compounds

D-arabinose − L-arabinose + D-ribose + D-xylose + D-glucose +D-mannose + D-galactose + L-rhamnose − D-fructose + L-sorbose −maltose + sucrose + lactose − melibiose − cellobiose + trehalose −raffinose − melezitose − α-methyl-D-glucoside − arbtin + esculin −salicin − dextrin + soluble starch + inulin + methanol − ethanol +adonitol (ribitol) − inositol − erythritol + D-mannitol + D-sorbitol −dulcitol − xylitol + glycerin + DL-lactate − succinate + citrate +

The properties of the present strain are similar to those of the genusTrichosporon in view of yeast classification according to the aboveliterature (The Yeasts, A Taxonomic Study). However, the properties ofthe present strain do not agree with those of any species of the genusTrichosporon in respect of color reaction with diazonium blue B,decomposition of urea, fermentation of saccharides, assimilation ofKNO₃, etc. Due to the length of its blastic conidia, the present strainis classified as the genus Trichosporonoides, on the basis of theclassification method described in “The Black Yeasts, II: Moniliella andAllied Genera” edited by G. S. De Hoog in Studies in Mycology No. 19(1979) (CBS: CENTRAALBUREAU VOOR SCHIMMELCULTURES, The Netherlands).

In view of the species classification method described therein,Trichosporonoides oedocephalis CBS 649.66 is different from the presentstrain in that while the former synchronically forms conidia at the topof a stalk, the present strain does not. Comparison of colony growth ona corn meal agar (culture at 25° C. for 2 weeks) indicated thatTrichosporonoides oedocephalis showed delayed growth with colonies of15.5 to 17 mm in diameter. Further, the surface of the colonies wasblack brown, and formation of aerial hyphae was not observed. On theother hand, the present strain showed vigorous growth with colonies of31 to 34 mm in diameter, and the surface of the colonies turned grayishwhite due to vigorous formation of aerial hyphae.

On a potato glucose agar (culture at 25° C. for 2 weeks),Trichosporonoides oedocephalis showed moderate growth with colonies of22 to 22.5 mm in diameter. Further, the surface of the colonies waswrinkled and dark brown in the center and pale brown at the periphery,and thin formation of weak aerial hyphae was observed in places on thesurface of the colonies. On the other hand, the present strain showedvigorous growth with colonies of 33 to 34.5 mm in diameter. Further, thesurface of the colonies was flat and covered with vigorous aerial hyphaeto turn grayish white. On a YM agar (culture at 25° C. for 2 weeks),Trichosporonoides oedocephalis showed moderate growth with colonies of22 to 23 mm in diameter. The surface of the colonies was wrinkled andbrown, and the periphery was white to pale brown, and formation ofaerial hyphae was observed in places at the periphery of the colonies.On the other hand, the present strain showed vigorous growth withcolonies of 32 to 34 mm in diameter. Further, the surface of thecolonies was covered with vigorous aerial hyphae to turn grayish white.With respect to assimilation of carbon compounds, Trichosporonoidesoedocephalis was different from the present strain in that the latterassimilates D-xylose, xylitol and inulin while the former does not.

Trichosporonoides spathulata CBS 241.79 forms spoon-shaped hypha stalks,while the present strain does not. Comparison of colony growth in a cornmeal agar (culture at 25° C. for 2 weeks) indicated thatTrichosporonoides spathulata was different from the present strain(supra) in that the former became large with colonies of 50 mm or morein diameter but grew with pale yellowish brown in a very thin form anddid not form aerial hyphae. On a potato glucose agar (culture at 25° C.for 2 weeks), Trichosporonoides spathulata showed significantly vigorousgrowth with colonies of 51 to 53 mm in diameter, as compared with growthof the present strain. Further, Trichosporonoides spathulata wasdifferent from the present strain in that the surface of the formercolonies formed wrinkles radially from the center, and the colonies weredark brown in the center and pale brown at the periphery, and on thecolonies, grayish white aerial hyphae were formed densely in the centerand sparsely towards the periphery, while the surface of colonies of thepresent strain, as described above, was smooth and free of wrinkles andcovered with grayish white well-grown hyphae. On a YM agar (culture at25° C. for 2 weeks) too, Trichosporonoides spathulata showed morevigorous growth with colonies of 44.5 to 47 mm in diameter than thepresent strain. The surface of the colonies was slightly elevated in thecenter, wrinkles were formed radially from the center to the periphery,and the whole surface was pure white to form aerial hyphae, while thepresent strain had grayish white hyphae as described above. With respectto assimilation of carbon compounds, Trichlosporonoides spathulata wasdifferent from the present strain in that the former assimilatesmelezitose, raffinose, D-sorbitol, DL-lactate, esculin, and salicin butthe latter does not. Further, Trichosporonoides spathulata does notrequire vitamins in the medium and is positive in a test of splitting oftallow, while the present strain requires vitamin and is negative in atest of splitting of tallow.

Trichosporonoides madida CBS 240.79 is considerably different from thepresent strain in that the former hardly forms hypha. Comparison ofcolony growth on a corn meal agar (culture at 25° C. for 2 weeks)indicated that Trichosporonoides madida showed moderate growth withcolonies of 23 to 25 mm in diameter and turned dark brown in the centerand pale brown at the periphery, and aerial hyphae were not formed. Onthe other hand, the present strain showed vigorous growth and formedaerial hyphae well, as described above.

On a potato dextrose agar (culture at 25° C. for 2 weeks) too,Trichosporonoides madida is different from the present strain. That is,Trichosporonoides madida is different from the present strain in thatthe former shows moderate growth with colonies of 22 to 24.5 mm indiameter, the colonies are black brown, and the surface is elevated toform some lumps, and formation of aerial hyphae is not observed. On a YMagar (culture at 25° C. for 2 weeks) too, Trichosporonoides madida,unlike the present strain, showed moderate growth with colonies of 21 to22 mm in diameter. The surface of the colonies was, unlike the presentstrain, roughly elevated and dark brown, and the periphery was palebrown. Formation of aerial hyphae was hardly observed. With respect tofermentation of saccharides, Trichosporonoides madida is different fromthe present strain in that the former does not ferment galactose andsucrose. It is reported its fermentation of sucrose is positive in aliterature of A. T. Martinez (Studies in Mycology No. 19), but isnegative in a literature of G. Douglas and Inglis et al. (G. DouglasInglis, Lynne Sigler, Mark S. Goettel, TRICHOSPORONOIDES MEGACHILIENSIS,A NEW HYPHOMYCETE ASSOCIATED WITH ALFALFA LEAFCUTTER BEES, WITH NOTES ONTRICHOSPORONOIDES AND MONILIELLA, Mycologia, 84(4), 1992, pp. 555-570),and this agreed with a test result of the present inventor, so itsfermentation of sucrose was assumed to be negative. With respect to theassimilation of carbon compounds, Trichosporonoides madida is differentfrom the present strain in that the latter assimilates galactose andinulin, while the former does not.

In view of the classification method described in the literature of G.Douglas and Inglis et al. (supra), Trichosporonoides nigrescens CBS268.81 is different from the present strain in that the former neithergrows at 37° C. nor ferments sucrose. With respect to assimilation ofcarbon sources, Trichosporonoides nigrescens is different from thepresent strain in that the former does not assimilate L-arabinose andD-xylose but assimilates D-sorbitol. Comparison of colony growth on acorn meal agar (culture at 25° C. for 2 weeks) indicated thatTrichosporonoides nigrescens was different from the present strain inthat the former showed weak growth with colonies of 9 to 9.5 mm indiameter. The colonies were dark black brown in the center and palebrown at the periphery, and formation of aerial hyphae was not observed.On the other hand, the present strain showed vigorous growth, and aerialhyphae were formed well, as described above.

On a potato glucose agar (culture at 25° C. for 2 weeks) too,Trichosporonoides nigrescens is different from the present strain. Thatis, Trichosporonoides nigrescens, unlike the present strain, showedmoderate growth with colonies of 17.5 to 19 mm in diameter, and thecolonies were black brown and the surface was elevated to form somelumps, and formation of aerial hyphae was not observed. Thesecharacteristics are different from those of the present strain. On a YMagar (culture at 25° C. for 2 weeks) too, Trichosporonoides nigrescensshowed considerably delayed growth with colonies of 13 to 14.5 mm indiameter, as compared with growth of the present strain. The surface ofcolonies was dark brown, and was elevated to form some lumps, andformation of aerial hyphae was not observed. These characteristics aredifferent from those of the present strain.

Similarly, in view of the classification method described in theliterature of G. Douglas and Inglis et al. (supra), Trichosporonoidesaustraliense (Ramirez, 1989) is different from the present strain inthat the former ferments lactate but does not assimilate L-arabinose andD-xylose, as opposed to the latter which does not ferment lactose butassimilates L-arabinose and D-xylose. Further, Trichosporonoidesaustraliense is different from the present strain in that the former ispoor in sugar resistance and does not grow on a medium containing 50%glucose, but the latter grows well even on a medium containing 60%glucose. Furthermore, Trichosporonoides australiense does not produceurease, so it is negative both in decomposition of urea and in colorreaction with diazonium blue B, whereas the present strain is positivein both.

Trichosporonoides megachiliensis CBS 567.85 is different from thepresent strain in that the former assimilates neither nitrates norL-arabinose, D-xylose, xylitol and inulin. Comparison of colony growthon a corn meal agar (culture at 25° C. for 2 weeks) indicated thatTrichosporonoides megachiliensis showed growth with colonies of 28 to29.5 mm in diameter, similar to growth of the present strain, but thesurface of colonies was flat and grew with black brown in a thin form,and aerial hyphae formed were very thin and weak. On the other hand, theaerial hyphae of the present strain were formed well so that the browncolor of the colony base could not be seen, and the color of thecolonies was thereby made grayish white.

On a potato glucose agar (culture at 25° C. for 2 weeks) too,Trichosporonoides megachiliensis is different from the present strain.That is, Trichosporonoides megachiliensis showed growth with colonies of25 to 27 mm in diameter, similar to the growth of the present strain.However, the colonies of Trichosporonoides megachiliensis, unlike thoseof the present strain, hardly formed aerial hyphae and the surfacethereof was flat and black brown. Further, the edges of colonies in theperiphery, unlike the colonies of the present strain, elongated radiallyinto the medium in a unique form similar to a burr. On a YM agar(culture at 25° C. for 2 weeks), Trichosporonoides megachiliensis showedvigorous growth with colonies of 29.8 to 30.5 mm in diameter, almostsimilar to growth of the present strain. However, formation of aerialhyphae was limited to a part of the surface of colonies e.g. about halfof the surface, as opposed to the present strain which formed aerialhyphae over the whole surface of colonies.

Accordingly, the present strain is a new species which though belongingto the genus Trichosporonoides, differs from the previously reportedTrichosporonoides oedocephalis, Trichosporonoides spathulata,Trichosporonoides madida, Trichosporonoides nigrescens,Trichosporonoides australiense, and Trichosporonoides megachiliensis.The present inventor named this new species Trichosporonoidskounosuensis. Besides the above novel strain, any mutant thereofobtained from the present new species naturally or artificially by suchtreatments as ultraviolet irradiation and mutagenesis agent also fallsunder the scope of the present invention, as long as it has an abilityto produce polyol.

The culture of the present strain is conducted under aerobic cultureconditions in a liquid medium containing a carbon source, a nitrogensource, inorganic salts etc.

The carbon source includes saccharides such as glucose, fructose,sucrose etc., and a starch-saccharified liquor containing thesesaccharides, and sugars such as sweet potato syrup, beet syrup etc. Theconcentration of the saccharides in the medium is 20 to 60%, preferably30 to 50%.

The nitrogen source includes nitrogenous compounds utilizable by themicroorganism, such as yeast extract, peptone, malt extract, corn steepliquor, ammonia water, ammonium salts, urea, nitrates etc.

Phosphates, magnesium salts, calcium salts, potassium salts, iron salts,manganese salts etc. are suitably used as the inorganic salts.

Culturing is conducted usually at a culture temperature of 25 to 40° C.,preferably 35 to 39° C. for 3 to 10 days during which polyol mainlycontaining erythritol, glycerin and ribitol is accumulated in theculture medium. The total yield of polyol (yield relative to sugar) is35 to 45% in the case of sugar concentration in the medium of 20 to 50W/V %, and for example 43.7% in the case of glucose concentration in themedium of 30 W/V %.

The method of recovering the polyol accumulated in the medium may beeffected in any method known in the art, for example by removing themicrobial cells by filtration or centrifugation, followed bypurification of the polyol by a suitable combination of treatment withion-exchange resins, absorption chromatography, extraction with solvent,crystallization by concentration under cooling, and so on. The polyolmay be purified by decoloration with active carbon or recrystallizationgenerally used for removing impurities.

Hereinafter, the examples of the present invention are described indetail by reference to the Examples, which are not intended to limit thepresent invention.

EXAMPLE 1 Comparison of the Amounts of Polyol Produced at DifferentCulture Temperatures

Trichosporonoids kounosuensis 7E-1 (FERM BP-6572) was inoculated into ayeast extract medium (30 W/V % glucose, 1 W/V % yeast extract) andcultivated at 35° C. for 3 days under shaking. Then, the resultingculture liquid was inoculated at a concentration of 2% based on theamount of the medium into the same yeast extract medium previouslyintroduced into an L-shaped culture tube, and the microorganism wascultured for 6 days at 60 rpm at a temperature in the range of 15.9 to46.2° C. in a shake temperature gradient incubator (Model TN-2148,Advantec Toyo K. K.). Then, the amounts of polyol (g/L) produced atdifferent temperatures were compared.

The amount of polyol produced and the amount of glucose remaining in theculture were determined by quantification in high performance liquidchromatography (HPLC) (Model RID-6A, Shimadzu Corporation). Forcomparison, the growth of the microorganism in the culture was alsoexpressed in terms of culture turbidity (absorbance at 660 nm×degree ofdilution of the culture). The results are shown in Table 1.

TABLE 1 Culture Polyol Production (g/L) Temp. (° C.) turbidity glucoseerythritol glycerin ribitol 15.9 42.7 216.0 13.8 11.2 2.7 18.3 44.9186.1 20.7 13.3 5.4 21.0 53.1 160.8 29.5 16.2 5.2 23.5 50.1 123.7 35.116.2 6.8 26.1 49.6 85.3 44.2 20.4 12.9 28.7 64.9 37.3 68.3 38.0 31.231.3 77.7 5.4 82.0 41.9 33.8 33.9 101.9 0 92.5 35.1 28.6 36.7 84.5 085.9 31.6 12.7 39.4 56.5 0 111.0 17.8 10.5 42.7 5.5 278.8 5.0 6.1 0 46.23.8 296.7 3.0 0 0

EXAMPLE 2 Glucose Concentration and Polyol Production

Trichosporonoids kounosuensis 7E-1 (FERM BP-6572) was inoculated into ayeast extract medium (30 W/V % glucose, 1 W/V % yeast extract) andcultured at 35° C. for 3 days under shaking. Then, the resulting cultureliquid was inoculated at a concentration of 2% based on the amount ofthe medium into a sugar concentration test medium previously introducedinto an Erlenmeyer flask, that is, a yeast extract medium (C/N ratio inthe yeast extract medium was constant) prepared at a glucoseconcentration of 20, 30, 40 or 50 W/V %, and the microorganism wascultured at 220 rpm at 35° C. The culture was continued until theglucose in the medium was almost consumed (115 to 157 hours). The amountof polyol produced in the culture was determined by quantification inHPLC (Model RID-6A, Shimadzu Corporation). The results are shown inTable 2. The yield relative to glucose in the table is the yield oftotal polyol relative to consumed glucose.

TABLE 2 Glucose Total Polyol Conc. Culture Polyol (g/L) (yield relative(W/V %) Time erythritol glycerin ribitol to Glucose) 20 115 67.7 12.16.7  86.5(43.9%) 30 115 91.5 25.3 14.4 131.2(43.7%) 40 141 115.2 42.516.1 173.7(43.4%) 50 157 97.4 56.4 13.2 167.0(35.9%)

EXAMPLE 3 Sucrose Concentration and Polyol Production

Trichosporonoides kounosuensis 7E-1 (FERM BP-6572) was inoculated into ayeast extract medium (30 W/V % glucose, 1 W/V % yeast extract) andcultured at 35° C. for 3 days under shaking. Then, the resulting culturewas inoculated at a concentration of 2% based on the amount of themedium into a sucrose concentration test medium previously introducedinto an Erlenmeyer flask, that is, a sucrose yeast extract medium (C/Nratio in the yeast extract medium was constant) prepared at a sucroseconcentration of 20, 30, 40 or 50 W/V %, and the microorganism wascultured at 220 rpm at 35° C. The culture was continued until thesucrose in the medium was almost consumed (115 to 157 hours). The amountof polyol produced in the culture was determined by quantification inHPLC (Model RID-6A, Shimadzu Corporation). The results are shown inTable 3. The yield relative to sucrose in the table is the yield oftotal polyol relative to consumed sucrose.

TABLE 3 Sucrose Total Polyol Conc. Culture Polyol (g/L) (yield relative(W/V %) Time erythritol glycerin ribitol to Glucose) 20 115 64.4 2.7 5.4 72.5(36.7%) 30 115 99.2 9.8 8.0 117.0(39.3%) 40 141 142.9 10.5 5.9159.3(40.2%) 50 157 157.4 14.9 4.2 176.5(35.5%)

EXAMPLE 4 Fructose Concentration and Polyol Production

Trichosporonoides kounosuensis 7E-1 (FERM BP-6572) was inoculated into ayeast extract medium (30 W/V % glucose, 1 W/V % yeast extract) andcultured at 35° C. for 3 days under shaking. Then, the resulting culturewas inoculated at a concentration of 2% based on the amount of themedium into a sugar concentration test medium previously introduced intoan Erlenmeyer flask, that is, a fructose yeast extract medium (C/N ratioin the yeast extract medium was constant) prepared at a fructoseconcentration of 40 W/V %, and the microorganism was cultured at 220 rpmat 35° C. for 10 days. As a result, 192.1 (g/L) polyol (i.e. erythritol,glycerin and ribitol in total) was produced in the culture medium.

EXAMPLE 5

Trichosporonoides kounosuensis 7E-1 (FERM BP-6572) was inoculated into ayeast extract medium (30 W/V % glucose, 1 W/V % yeast extract) andcultured at 35° C. for 3 days under shaking. Then, the resulting culturewas inoculated at a concentration of 2% based on the amount of themedium into a sugar concentration test medium previously introduced intoan Erlenmeyer flask, that is, a yeast extract medium (C/N ratio in theyeast extract medium was constant) prepared at a glucose concentrationof 30 or 40 W/V %, and the microorganism was cultured at 220 rpm at38.5° C. The culture was continued until the glucose in the medium wasalmost consumed (113 or 143 hours). The amount of polyol produced in theculture was determined by quantification in HPLC (Model RID-6A, ShimadzuCorporation). The result indicated that the total yield of polyol was43.7% in the 30% glucose medium, and the total yield of polyol was 44.0%in the 40% glucose medium.

INDUSTRIAL APPLICABILITY

The novel microorganism of the present invention has taxonomicalproperties different from those of any known species of the genusTrichosporonoides, and is a useful microorganism having a high abilityto produce polyol such as erythritol. Further, polyol such as erythritolcan be produced efficiently by use of said microorganism.

What is claimed is:
 1. Trichosporonoides kounosuensis 7E-1 (FERMBP-6572) which has an ability of accumulating polyol in the culturemedium by culturing in a medium containing sugar.
 2. A process forproducing polyol, which comprises culturing Trichosporonoideskounosuensis 7E-1 (FERM BP-6572) in a medium at a sugar concentration of20 to 60% and recovering polyol accumulated in the medium.
 3. Theprocess for producing polyol according to claim 2, wherein the medium isa medium containing glucose, fructose or sucrose as main components. 4.The process for producing polyol according to claim 2 wherein the polyolis a polyol containing erythritol, glycerin and ribitol as maincomponents.
 5. The process for producing polyol according to claim 2,wherein the concentration of the sugar in the medium is 20 to 60% andthe culturing is carried out at a culture temperature of 25 to 40° C. 6.The process for producing polyol according to claim 2, wherein theconcentration of the sugar in the medium is 30 to 50% and the culturingis carried out at a culture temperature of 35 to 39° C.
 7. The processfor producing polyol according to claim 2, wherein the polyolaccumulated in the medium has a yield of 35% or more relative tosaccharide.
 8. The process, for producing polyol according to claim 3,wherein the polyol is a polyol containing erythritol, glycerin andribitol as main components.
 9. The process for producing polyolaccording to claim 3, wherein the concentration of the sugar in themedium is 20 to 60% and the culturing is carried out at a culturetemperature of 25 to 40° C.
 10. The process for producing polyolaccording to claim 4, wherein the concentration of the sugar in themedium is 20 to 60% and the culturing is carried out at a culturetemperature of 25 to 40° C.
 11. The process for producing polyolaccording to claim 8, wherein the concentration of the sugar in themedium is 20 to 60% and the culturing is carried out at a culturetemperature of 25 to 40° C.
 12. The process for producing polyolaccording to claim 3, wherein the concentration of the sugar in themedium is 30 to 50% and the culturing is carried out at a culturetemperature of 35 to 39° C.
 13. The process for producing polyolaccording to claim 4, wherein the concentration of the sugar in themedium is 30 to 50% and the culturing is carried out at a culturetemperature of 35 to 39° C.
 14. The process for producing polyolaccording to claim 8, wherein the concentration of the sugar in themedium is 30 to 50% and the culturing is carried out at a culturetemperature of 35 to 39° C.
 15. The process for producing polyolaccording to claim 11, wherein the concentration of the sugar in themedium is 30 to 50% and the culturing is carried out at a culturetemperature of 35 to 39° C.
 16. The process for producing polyolaccording to claim 3, wherein the polyol accumulated in the medium has ayield of 35% or more relative to saccharide.
 17. The process forproducing polyol according to claim 4, wherein the polyol accumulated inthe medium has a yield of 35% or more relative to saccharide.
 18. Theprocess for producing polyol according to claim 5, wherein the polyolaccumulated in the medium has a yield of 35% or more relative tosaccharide.
 19. The process for producing polyol according to claim 6,wherein the polyol accumulated in the medium has a yield of 35% or morerelative to saccharide.
 20. The process for producing polyol accordingto claim 8, wherein the polyol accumulated in the medium has a yield of35% or more relative to saccharide.
 21. The process for producing polyolaccording to claim 11, wherein the polyol accumulated in the medium hasa yield of 35% or more relative to saccharide.
 22. The process forproducing polyol according to claim 15, wherein the polyol accumulatedin the medium has a yield of 35% or more relative to saccharide.